$\begingroup$This makes sense! But, I’m confused how you got 4 as the $y$ value in that point since when $x = 2$ on the graph, $y=0$.$\endgroup$
– EllaNov 5 '18 at 2:41

1

$\begingroup$@Ella 4 is the $x$ value, not the $y$ value. It's just eyeballing the graph of $f'(x)$. It reaches a local minimum at $x=4$ and a local maximum at $x=2$, so $f'(x)$ is decreasing between those points.$\endgroup$
– Parcly TaxelNov 5 '18 at 2:44